Because an ocular optical system is very complicated and an actual eye is very difficult to handle, various eye simulations have been proposed as a standard optical model of an eyeball. Studies on the optical characteristics of an eyeball (e.g., changes of various optical images when an intraocular lens is implanted) have been conducted by using such simulated eyes or by computer simulation using optical constants calculated from such simulated eyes.
Various new types of lenses such as a progressive multi-focus lens are being developed in the field of eyeglass lenses. However, it has heretofore been a problem that it has not been possible to objectively observe how things are seen when a subject wears these eyeglass lenses. This problem has been a big obstacle in the research and development of eyeglass lenses.
The inventors of the present invention have devised an ocular optical simulation system (Japanese Patent Publication No. Hei. 301887) for simulating a retinal image obtained when a subject wears an eyeglass lens. This system has an eye simulating lens and comprises a lens system for simulating an optical system of human eyes when a subject wears an eyeglass lens utilizing the eye simulating lens, an eyeglass lens to be simulated and an image-pickup means for picking up an image formed by the lens system, in order to simulate a retinal image of a subject wearing the eyeglass lens.
It is necessary to consider differences between ordinary optical systems (camera, telescope and the like) in simulating the optics of an eyeglass lens and an eyeball. That is, although an object in a wide range can be imaged on the face of a film at one time in case of the ordinary optical system, e.g., a camera, as shown in FIG. 14a, the eyeball receives an image in a wide range while turning centering about a turning point as shown in FIG. 14b. This is because not all images imaged on the retina of the eye are perceived as clear images and only an image in a narrow area of the fovea part having high resolution is seen as a clear image. Accordingly, it is necessary to take the rotary movement (ocular movement) centering on the turning point of the eyeball into consideration in simulating the eyeglass lens and the eyeball as one optical system.
Furthermore, a solid (three-dimensional) standard measuring object (e.g., chart) suited for the purpose of using the eyeglass lens (e.g., far-sighted use, near-sighted use and the like) is required for the above-mentioned reason to evaluate the performance of the eyeglass lens. However, it is very difficult to dispose the measuring object (chart) widely in three-dimensional space because, for example, an appropriate installation space must be assured.
Accordingly, it is an object of the present invention to provide an artificial vision system which can simulate a retinal image at each eye position when a subject observes a standard object by turning his eyeball with respect to the eyeglass lens.
Another object of the present invention is to provide an artificial vision system which can simulate the positional relationship among the eyeglass lens, the eyeball and the standard object at each eye position when a subject views the standard object through the eyeglass lens by turning his eyeball to the standard object set at a predetermined position, and which can simulate a retinal image at each position of the eyeball.